Spark plug



1949 R. J. L. DUTTERER 2,478,656

SPARK PLUG Filed July 1'7, 1946 I N VEN TOR.

Patented Aug. 9 1949 SPARK PLUG Rex J t L. Dutterer', Hastings, Mich, assignor to Hastings Manufacturing Company, Hastings,

Mich.

Application July it, 1946, serial No. 684,160

7 Claims.

This invention relates to improvements in spark plug.

The principal objects of this invention are:

First, to provide an improved sealbetween the sleeve and insulator of a spark plug which will effectively transfer heat away from the insulator.

Second, to provide a spark plug with an eifec tive seal between the sleeve and insulator, which spark plug may be easily and inexpensively formed with a reduced amount of material.

Third, to provide a seal between the sleeve and insulator of a spark plug which maybe accurately controlled for uniformity in mass production.

Fourth, to provide an effective seal between the insulator and sleeve of a spark plug which will permit relative expansion between the sleeve and the insulator without breaking the seal.

Fifth, to provide a sleeve for a; sparkplug which will not transmit stresses to the insulator as it expands and contracts under varying operating temperatures". 7

Other objects relating to details and economies of the invention will appear from the description to follow. The invention is defined and pointed out in the claims.

The drawings of which there is one sheet illustrate a preferred form and two modified forms of the invention.

Fig. 1 is an elevational view partially in cross: section of a spark plug embodying the preferred form of the invention.

Fig. 2 is an enlarged fragmentary cross-sectional view showing the details of the seal between the insulator and sleeve shown in Fig. -1-.

3 is an elevational view showing a first modified form of spark plug.

Fig. 4 is an enlarged fragmentary cross-sectional View taken along the line 4-4 in Fig 3.

Fig. 5 is an enlarged cross-sectional view sl milar to Fig. 4 and illustrating a second modified form of the invention. Y

Fig. 6 is a perspective view of the collar illustrated in Figs. 4 and 5. 7

Referring now to the drawings, the reference character 5 indicates a sleeve member provided with a threaded portion 2 arranged to be secured in an engine and a side electrode 3 arranged to coope c with the center electrode 4 mounted in the insulator member 5. The sleeve l defines a central bore 6 having an enlarged upper portion 7 arranged to receive the enlarged shoulder por tion 8 of the insulator. The junction between the upper and lower sections of the bore is sloped downwardly as at 9 to seat against the lower surface of the shoulder 8 on the insulator.-

The vertical surface of the shoulder 8 is metalized as indicated at In by a process in which the molten metal is sprayed on the surface of the insulator. This metal spray process deposits a layer of metal which adheres tightly and permanently to the insulator. The surface of the metal ized layer is then ground to fit loosely Within the upper portion of the sleeve I. A layer of brazing metal H is then fused between the inner surface of the sleeve and the metalized layer on the insulator. This may be accomplished con veniently by placing the insulator in the sleeve and by placing a ring of brazing metal over the upper edge of the shoulder 8 as indicated by the dotted lines at l2 in Fig. 2. The assembly may then be placed in a furnace and raised to a temperatu're which will melt the ring of brazing inaterial but which will not melt the metalized layer on the insulator. The brazing metal will then flow into the space between the sleeve and the insulator and will solidify to form a gas-tight seal between the sleeve and the insulator. The mating beveled surfaces on the sleeve and the shoulder of the insulator will properly align the insulator in the sleeve during assembly.

The bond between the nietalized layer and the shoulder of the insulator may be improved by coating" the shoulder 8 with a glaze of low melting point before applying the metal.

Attention is invited to the fact that Since no sealing gaskets are required at the ends of the shoulder 8, the length of the metal sleeve may be reduced as there is no need for an upper rim or bushing to clamp the gaskets to the shoulder. The overall length of the insulator may therefore be reduced and still obtain the same effective insulator or flash over length as indicated by the dotted lines in Fig. l.

in the modified form of the invention illustrated in Figs. 3 and 4, the upper nut-shaped portion of the sleeve I3 is provided with a series of radially extending slots l4 which will permit the top of the sleeve to expand and contract without applying any pressure to the insulator IS. The shoulder I6 formed on the insulator I5 is elongated over that shown in Figs. 1 and 2 and a relatively narrow band around the middle of the shoulder is treated with the metalizing process as at H. The band I! is then brazed to the lower inside surface of a collar l8 as is indicated at H). The upper outside surface of the collar i8 is brazed to the upper inside surface of the sleeve as is indicated at 20. Thus any change of size of the sleeve due to expansion or contraction will result in distortion or flexing of the collar 18 without the transmission of objectionable stress to the insulator I5. Since the slots l4 prevent the forming of a seal as in the preferred form of spark plug, a seal is obtained between the sleeve and the insulator by positioning a gasket 2| between the lower surface of the shoulder 16 and the cooperating shoulder formed on the inside of the sleeve. While the connection between the shoulder and the sleeve permits expansion of the sleeve, it still provides a firmly bonded.

connection between the two members which will have a predetermined high coefficient of heat conductivity which is desirable in obtaining uniformly operating spark plugs.

In the modified form of the invention illustrated in Fig. the sleeve 22 is not slotted as that shown in Figs. 3 and 4. The insulator 23 has the layer of metalizing material 24 applied to the upper end of the shoulder 25. The collar 26 is the same as that illustrated in Figs. 3 and 4 but is connected to the metalizing layer 24 along its upper inside surface as at 2'5, and to the sleeve along its lower outside surface as at 28. contraction of the sleeve to be compensated for by bending of the collar 26 and at the same time provides a continuous fused seal completely around the sleeve and the insulator. There being no need for a second seal, the gasket shown at 2! in Fig. 4 is omitted in this form of the invention.

The various forms of the invention just described all employ a fused metallic bond between the insulator and sleeve of the spark plug which will have effective predeterminable heat conducting properties which may be accurately controlled in all spark plugs manufactured in any one of the designs shown. The operating characteristics of the plugs may then be predeterm-ined and accounted for in designing other features of the spark plug.

The invention has been illustrated and described in embodiments which have been found to be highly satisfactory. No attempt has been i made to show other possible adaptations as it is believed that this disclosure will enable those skilled in the art to adapt the invention as may be desired.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A spark plug comprising a metallic sleeve member adapted to be installed in an engine and defining a central bore therethrough, an insulator positioned in said bore, the diameter of said insulator being smaller than the diameter of said bore in said sleeve, a band of metal sprayed around said insulator, and a cylindrical metallic collar positioned in said bore and around said insulator, said metallic collar being bonded at one end to said band of metal on said insulator and at the other end to the inside of said sleeve for a substantial length of said bore.

2. A spark plug comprising a metallic sleeve member adapted to be installed in an engine and defining a central bore having a lower portion of reduced cross-section with an upwardly sloping wall around the upper end thereof, an insulator member having an enlarged shoulder portion arranged to fit within the upper portion of said bore, a band of metal sprayed around said shoulder on said insulator and positioned within the upper portion of said bore, a metallic collar positioned around said shoulder on said insulator This construction permits expansion and and within the upper portion of said bore, the lower end of said metallic collar being brazed to said metal band on said insulator, the upper end of said metallic collar being brazed to the inside of said bore, and a sealing gasket positioned on said sloping wall in said bore and in sealing contact with the lower surface of said shoulder on said insulator, the upper portion of said sleeve defining a series of radial slots extending between said bore and the outer surface of said sleeve.

3. A spark plug comprising a metallic sleeve member adapted to be installed in an engine and defining a central bore having a lower portion of reduced cross-section, an insulator member having an enlarged shoulder portion arranged to fit within the upper portion of said bore, a band of metal fused around said shoulder on said insulator, a metallic collar positioned around said shoulder on said insulator and Within the upper portion of said bore, the lower end of said metallic collar being brazed to said metal band on said insulator, the upper end of said metallic collar being brazed to the inside of said bore, and a sealing gasket positioned in said bore and in sealing contact with the lower surface of said shoulder on said insulator, the upper portion of said sleeve defining a series of slots extending between said bore and the outer surface of said sleeve.

4. A spark plug comprising a metallic sleeve member adapted to be installed in an engine and defining a central bore having a lower portion of reduced cross-section with an upwardly sloping shoulder around the upper end thereof, an insulator member having an enlarged shoulder portion arranged to fit within the upper portion of said bore, a band of metal sprayed around said shoulder on said insulator and positioned within the upper portion of said bore, and a metallic collar positioned around said shoulder on said insulator and within the enlarged portion of said bore, the upper end of said metallic collar being brazed to said metal band on said insulator, the lower end of said metallic collar being brazed to the inside of said bore.

5. A spark plug comprising a metallic sleeve member adapted to be installed in an engine and defining a central bore having a lower portion of reduced cross-section, an insulator member having an enlarged shoulder portion arranged to fit within the upper portion of said bore, a band of metal around said shoulder on said insulator and positioned within the upper portion of said bore, and a metallic collar positioned around said shoulder on said insulator and within the enlarged portion of said bore, the upper end of said metallic collar being fused to said metal band on said insulator, the lower end of said metallic collar being fused to the inside of said bore.

6. A spark plug comprising a metallic sleeve member adapted to be installed in an engine and defining a central bore, an insulator member arranged to fit within said bore, a band of metal sprayed around said insulator and positioned within said bore, and a metallic collar positioned around said insulator and within said bore, the upper end of said metallic collar being brazed to said metal band on said insulator, the lower end of said metallic collar being brazed to the inside of said bore.

7. A spark plug comprising a metallic sleeve member adapted to be installed in an engine and defining a central bore, an insulator member ar- 5 ranged to fit within said bore, a band of metal sprayed around said insulator and positioned within said bore, and a metallic collar positioned around said insulator and within said bore, the upper end of said metallic collar being bonded to said metal band on said insulator, the lower end of said metallic collar being bonded to the inside of said bore.

REX J. L. DU'I'IERER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Number Name Date Schmidt Jan. 3, 1911 Owens June 1'7, 1919 Braselton July 29, 1919 Rabezzana. Mar. 13, 1934 Stupakofi Dec. 28, 1937 Hurley Nov. 8, 1938 Vatter Dec. 6, 1938 King Feb. 10, 1942 FOREIGN PATENTS Country Date Great Britain Nov. 26, 1937 

